Dog owners and advocates are gathering at Fort Mason in San Francisco on Monday to protest a proposal to drastically reduce off-leash dog areas in the Golden Gate National Recreation Area.

The proposal, released by the National Park Service on Jan. 14, would reduce the size of off-leash areas for dogs at 21 spots throughout the recreation area, including at San Francisco locations such as Ocean Beach, Crissy Field and Fort Mason.

David Emanuel, one of the organizers of Monday's rally, said he opposes the proposal because it would decrease what are already "very few places people can take their dogs for outdoor exercise" in San Francisco.

Before the 5:30 p.m. rally, the National Park Service is holding an open house meeting at Fort Mason at 4 p.m., and Emanuel said hundreds of people are expected to attend in opposition of the proposal.

The park service said in its proposal that the "increased expectations for use of the park for dog recreation have resulted in controversy, litigation, and compromised visitor and employee safety, affecting visitor experience and resulting in resource degradation."

Emanuel disagreed with the park service's assessment of the various parts of the recreation area, saying "it's a very friendly place, and environmentally a very healthy place."

Emanuel, who lives in the city's Glen Park neighborhood, said he takes his 7-year-old American Staffordshire terrier to Fort Funston, where "it's cold, foggy, and windy, and it's generally just dogs and hang gliders."

He said if the proposal is enacted by the park service, he is "going to have to go somewhere closer to home," such as a city recreation center or park.

That possibility is one of the reasons San Francisco Supervisor Scott Wiener has expressed concern over the proposal and is calling for the board to hold a committee hearing on the issue.

Wiener said the reduction in off-leash space in the national park could lead to a corresponding increase in use at neighborhood parks in the city.

He said his hearing will likely be held in the next month or so before the park service's public comment period for the proposal ends on April 14.

The park service held its first of four open house meetings on the proposal on Wednesday in Mill Valley.

The two meetings in San Francisco are scheduled for Saturday at San Francisco State University's Seven Hills Conference Center and Monday at Fort Mason.

The last of the four meetings is scheduled for next Wednesday at Cabrillo Elementary School in Pacifica.

For more information on the park service's proposal, visit www.nps.gov/goga/parkmgmt/dog-management.htm.